I'm slowly making my way through this thread and am wondering about simple power distribution for servos. I like the looks of the Smart Fly products however I don't really need all of the features. My 104 will be A100-10 powered so I don't need optical kill, throttle servo, ignition or any other liquid power goodness.
I like the dual CC BEC Pro's feeding 2 receivers like the KM or 1 receiver like AJ. However, connecting the outputs of the CC BEC's together still makes me nervous.
Then I ran across the following product which seems to be quite interesting from a geek factor:

I'm slowly making my way through this thread and am wondering about simple power distribution for servos. I like the looks of the Smart Fly products however I don't really need all of the features. My 104 will be A100-10 powered so I don't need optical kill, throttle servo, ignition or any other liquid power goodness.
I like the dual CC BEC Pro's feeding 2 receivers like the KM or 1 receiver like AJ. However, connecting the outputs of the CC BEC's together still makes me nervous.
Then I ran across the following product which seems to be quite interesting from a geek factor:

My goal is to keep it as simple and light as possible. I'm using a Futaba HV Rx, 7955 servos all around and the Hitec programmer for setup.

Any thoughts, links or whatever will be appreciated.

Doug B.

the detail of my setup is that the power wires to the servos go straight to the BEC's, not to the receivers... so you can just divvy the servo load between the BEC's. connect the negative wires of the BEC's so that they all have the same ground connection, and run a power wire to the receiver. this allows the BEC's to still be independent of each other, while still driving all the servos. My current 104 has three BEC-Pro's, one wing + an elevator servo per BEC, rudder, throttle and whatever else is on the third BEC... the red output wires of the BEC's are not joined...

I'm slowly making my way through this thread and am wondering about simple power distribution for servos. I like the looks of the Smart Fly products however I don't really need all of the features. My 104 will be A100-10 powered so I don't need optical kill, throttle servo, ignition or any other liquid power goodness.
I like the dual CC BEC Pro's feeding 2 receivers like the KM or 1 receiver like AJ. However, connecting the outputs of the CC BEC's together still makes me nervous.
Then I ran across the following product which seems to be quite interesting from

My goal is to keep it as simple and light as possible. I'm using a Futaba HV Rx, 7955 servos all around and the Hitec programmer for setup.

Any thoughts, links or whatever will be appreciated.

Doug B.

F.W.I.W.:
I have 2 CC BEC's, each feeding a separate 8ch HV Futaba Rx, and each Rx operating half the airplane's servos. That's working fine for me. I will never hook two BEC outputs directly together because if they are even slightly different in output voltage, they will fight each other and generate unnecesary heat that may result in one or both BEC's burning out. Each receiver is running 1 elevator, 1 rudder, 1left & 1right aileron servo.

Thanks guys for the replies. Are you running 2S or 3S? I assume your packs are in the 3000 - 4000 mAh range?

Doug B.

Of the 12S 2P for my motor, I'm using one 6S of one of the Ps for one CC Pro and the other CC Pro uses a 6S from the other P. I've made a pair of Y connectors that plug between the 6S's that allow me to tap into just one 6S for each CC Pro. I never have to charge any batteries for the Rx/Servos. Using a separate 6S for each CC Pro gives me some battery redundancy. As for flight time, my batteries don't even know the Rx/servos exist and the plane is a little bit lighter.

I'm slowly making my way through this thread and am wondering about simple power distribution for servos. I like the looks of the Smart Fly products however I don't really need all of the features. My 104 will be A100-10 powered so I don't need optical kill, throttle servo, ignition or any other liquid power goodness.
I like the dual CC BEC Pro's feeding 2 receivers like the KM or 1 receiver like AJ. However, connecting the outputs of the CC BEC's together still makes me nervous.
Then I ran across the following product which seems to be quite interesting from a geek factor:

My goal is to keep it as simple and light as possible. I'm using a Futaba HV Rx, 7955 servos all around and the Hitec programmer for setup.

Any thoughts, links or whatever will be appreciated.

Doug B.

Quote:

Originally Posted by theKM

the detail of my setup is that the power wires to the servos go straight to the BEC's, not to the receivers... so you can just divvy the servo load between the BEC's. connect the negative wires of the BEC's so that they all have the same ground connection, and run a power wire to the receiver. this allows the BEC's to still be independent of each other, while still driving all the servos. My current 104 has three BEC-Pro's, one wing + an elevator servo per BEC, rudder, throttle and whatever else is on the third BEC... the red output wires of the BEC's are not joined...

What Aaron is talking about can be easily seen in the PDF. He helped me with the design and I put it to paper so I can understand it better. My intent was to use this setup but someone made me an offer I could not refuse on a smartfly board (FREE ). you can use a 2S 4000 or a 3S 2200... Hope it helps...

Files

Have this in a lot of Joe's planes. And he has even designed a new version of it for the 87shp.
The new version does not have any servo current running thru the receiver. He has the receiver
isolated from the servos just like a smartfly does. Dual battery circuit with isolated receiver power driving
6 servos directly. And all for about 15$, which I like a lot.

Using a separate 6S for each CC Pro gives me some battery redundancy. As for flight time, my batteries don't even know the Rx/servos exist and the plane is a little bit lighter.

Similar to what I do on my helicopters. My only hesitation on this method is if the ESC or motor overload / let the magic smoke out, you will no longer have power to the Rx and servos. In a 25+ pound aircraft that possibility concerns me enough to add a bit of weight and complexity for safety reasons.

Quote:

Originally Posted by hosam

What Aaron is talking about can be easily seen in the PDF. He helped me with the design and I put it to paper so I can understand it better. My intent was to use this setup but someone made me an offer I could not refuse on a smartfly board (FREE ). you can use a 2S 4000 or a 3S 2200... Hope it helps...

Super, thank you for the PDF. That helps me wrap my mind around his words. So many good choices.

Quote:

Originally Posted by jsmith285

Have this in a lot of Joe's planes. And he has even designed a new version of it for the 87shp.
The new version does not have any servo current running thru the receiver. He has the receiver
isolated from the servos just like a smartfly does. Dual battery circuit with isolated receiver power driving
6 servos directly. And all for about 15$, which I like a lot.

Thanks much! I ran across your original post and was going to ask for more info. You read my mind. How does the new version differ? I do like the idea of the isolated Rx power.

Thanks guys for all of the great help. Like most parts of the RC hobby there are many ways to solve this problem. I appreciate all of the options.

Here's the setup. SWB 4 inch offset arm, cables crossed, rudder cables going to the outermost control horn hole which is right on the rudder hingeline. The cables just go very slack through the travel and at full throw they're at their slackest. Obviously I have a geometry issue here. Speaking of geometry with 45 degrees of rudder throw the servo travels 50 degrees. This is both right and left so that's telling me I have greater distance at the control horn as the servo arm width.
From the SWB website, when crossing the cable I'm supposed to use an offset arm that's shorter the rudder control horn, which it is but it's not working. I do have a 3 inch offset arm and I didn't yet try this since I know others are running 4 inch swb arms on their 104s.

Just for kicks I ran the cables straight, not crossing them, still using the offset on the arm and it was better but not perfect.

I don't show it in the video but the cables are tight (not banjo tight, just snug) at the centered position.

The other issue is a jittery 7955 at center but I'll deal with that separately. Interestingly, when NOT crossing the cables there's zero jitter. I'm suspecting the jitter goes away with none-crossed cables since the cable drags a tad on the rear most bulkheads in the fuse and that probably dampens the centering jitter tendency. Also, when I connect the second 7955 it may dampen it as well. I'd like to get the cable issue fixed first though. Any ideas?

Bikeman, I just maiden my last week and my cables were the sames as your.
It works fine because when flying there is alway positive pressure on rudder keeping the cables tight, just as long as their tight around neutral it should be fine.
I would check them after the first couple of fights, mine got really loose due to cable stretch.

Oh as far as the 7955 jitter, that's their trait. What will help is if put a small piece of fuzzy Velcro between the rudder and fin where they pass over each other so it creates a slight friction at neutral should help with jitters

Oh as far as the 7955 jitter, that's their trait. What will help is if put a small piece of fuzzy Velcro between the rudder and fin where they pass over each other so it creates a slight friction at neutral should help with jitters

You know I just read a post from TheKM on this very subject. I'll definitely try this. Thanks.